Filling atomic orbitals creates an electronic structure pattern that makes elements with similar configurations (but different principle quantum numbers) have similar chemistry which thus explains the shape of the Periodic Table.
a. Explain how the atomic radii vary across the 2nd and 4th rows of the periodic table. Give a reason for the trends.
b. Explain how the ionization potentials vary across the second row. Note singularities, deviations from the overall trends. Explain.